Lactose

Lactose is a sugar present in cow's milk. Not everyone can digest milk sugar; these people are known as lactose intolerant. For a Lactose intolerant person, it is important to know how much lactose is in a food. Many lactose intolerant people can actually tolerate a small amount of lactose without discomfort. Some common ingredients, like whey, are high in lactose but may not be immediately recognized as a milk product.

Sugar of milk or milk sugar; a crystalline sugar present in milk, and separable from the whey by evaporation and crystallization. It has a slightly sweet taste, is dextrorotary, and is much less soluble in water than either cane sugar or glucose. Formerly called lactin.